In general, airbag devices are mounted on vehicles such as automobiles, where airbags are expanded and developed in cars in the event of an emergency, e.g., crash and rapid deceleration, so as to absorb shocks applied to occupants. Various types of airbag devices have been developed and adopted. Examples airbag devices include a driver airbag device incorporated in a steering, a passenger airbag device incorporated in an instrument panel, a side airbag device incorporated in a vehicle side portion or a seat, a curtain airbag device incorporated in an upper portion of a door, and a knee airbag device corresponding to knee portions of an occupant.
In general, the airbag device includes an airbag which is usually folded and which is expanded and developed in the event of an emergency, and an inflator to feed gas to the airbag. The inflator is connected to, for example, an ECU (electronic control unit) of a vehicle and is controlled on the basis of a measurement value of an acceleration sensor or the like. When the ECU detects or predicts crash or rapid deceleration of the vehicle, the inflator is ignited because of an ignition current from the ECU, an agent stored in the inside of the inflator is burnt to generate gas, and the gas is fed to the airbag.
In general, the gas spouted from the inflator is a high-temperature high-pressure gas and the vicinity of the spouting nozzle of the inflator has a heat-resistant pressure-resistant structure (for example, refer to PTL 1 to PTL 4). In particular, it is necessary that the curtain airbag (head side airbag) be expanded and developed in a wide range from a front seat to a rear seat and, in many cases, a large high-power inflator is employed to feed gas into the airbag.
PTL 1 describes a gas feed pipe having a bifurcated end. Also, PTL 2 describes a diffuser pipe provided with gas distribution holes. Also, PTL 3 describes a gas introduction pipe having a protruded portion at part of a circumferential side surface of a tubular body. Also, PTL 4 describes a cloth gas guide, thereby negating the need for a rigid gas guide.